Traditionally, playing cards have been supplied to a playing area or table in a casino by dealing from one or more shuffled decks of pre-printed cards. Although, in dependence on the thoroughness of the shuffle, initial cards are dealt from an almost complete pack with a fairly high degree of randomness, as the pack is of finite length, in practice the cards remaining available for dealing, decrease with each card dealt and, therefore, the randomness rapidly decreases, with the probability of any particular card being dealt progressively increasing to a much higher value than the probability prevailing with a fresh deck. Although casino operators deal from multiple decks and split the decks so that a substantial proportion of cards having undetected values cannot be dealt at that session, "card counting" remains a problem as significant swings in probability against the house are still detectable by the card counter.
As the payout of the game is usually calculated on a random basis assuming a full deck of cards, variations in amounts wagered following such card counting can result in the odds actually swinging substantially against the casino and the casino consequently loosing substantial sums of money.
In addition, considerable time and money can be spent on monitoring "card counters". Furthermore, the time needed to shuffle effectively several decks causes an undesirably costly hiatus in play with many players leaving the table during the shuffle, not to return. Considerable supplies of cards must also be kept in a safe while a watch must also be maintained for any marked recirculating cards.